Plants to 4 m tall. Rhizome short, tuberous, diameter unknown. Leaves: sheaths more or less lanuginose, with blackish margins; lamina narrowly elliptic-ovate to ellipticovate, 25–65 by 8–25 cm, base narrowly cuneate, apex acute or sometimes shortly acuminate, upper side dark dull green, lower side more or less lanuginose. Inflorescence repeatedly branched, with 2‑flowered cincinni; pedicels 0.5–1 cm long, to 2 cm in fruit, densely tuberculate below the ovary; primary bracts 12.5–16 cm long, obtuse, acute, or acuminate; branch bracts 4.5–14 cm long, acute; floral bracts broadly (ob)ovate to (ob)ovate, 0.5–2.5 cm long, obtuse to acute, persistent; bracteoles narrowly triangular to triangular-ovate, 1–2.5 cm long, acute; rachis, bracts, bracteoles, and sepals generally glaucous and more or less lanuginose. Flowers orange-red (to pale orange-yellow or red), erect, 4–7 cm long; sepals pale green to reddish pink, narrowly ovate-triangular, 1–1.5 by 0.3–0.5 cm, acute to acuminate; corolla orange-red, 3.5–6.5 cm long, petals erect, narrowly ovate-triangular, 3–5 by 0.4–0.6 cm, acute; staminodes 3 or 4, orangered, 5–7 cm long, free parts narrowly obovate to narrowly ovate-elliptic, 2.5–3.5 by 0.2–0.6 cm, erect, 1 slightly recurved; stamen orange-red, free part narrowly obovate, 2–2.5 by 0.4–0.8 cm, theca 0.5–0.7 cm long; style orange-red, free part narrowly elliptic, 1.5–3.5 by 0.3–0.4 cm. Fruit greenish, covered by purple to wine red-tipped tubercles, ellipsoid to obovoid, 2.5–4.5 by 2–2.5 cm. Seeds subglobose to broadly ellipsoid, 5–9 by 4–7 mm.
Canna bangii can be recognized by having erect, orange-red flowers with erect petals, inflorescences with persistent floral bracts, and pedicels densely tuberculate just below the ovary or fruit.
This species looks quite similar to C. indica, but differs by the persistence of its floral bracts, its somewhat longer, tuberculate pedicels (especially in fruit), and its preference for high altitudes.
Peru (Ayacucho, Cajamarca, Cuzco, Huánuco, Puno) and Bolivia (La Paz, Santa Cruz).
At elevations of 1400–2800 m; in shady, wet places in forest, along rivers, on forested slopes or roadsides, also in secondary vegetation.
This species has been found cultivated as an ornamental in Bolivia, La Paz.